1. Field of the Invention
The present invention relates to an image processing apparatus, a subject discrimination method, a program and a storage medium.
2. Description of the Related Art
A technique is known for enabling detection even when a portion of a detection target is shielded, as discussed in Japanese Patent Application Laid-Open No. 2007-47965. In this technique, a plurality of discriminators are generated by causing a plurality of discriminators to learn by using a detection target in which portions different from one another are occluded by dislocating a pattern clipping position, for example. Further, in this technique, detection is enabled when either one portion of the detection target is shielded by applying the plurality of discriminators on a parallel arrangement.
Now, consider a case in which, for example, a surveillance camera is installed on a ceiling of corridor, a video image of pedestrians passing through the corridor is captured from obliquely above, and a person is detected from the captured video image. In the video image obtained from the surveillance camera, a probability that a body part is hidden due to overlaps of people becomes higher in lower body regions than heads of the pedestrians with increasing crowding level. Further, a person who comes in a frame of the camera from immediately below the camera usually comes in the frame from the head. As a result, an occurrence probability of occlusion tends to become higher in a lower part in an entire body of a pedestrian.
The conventional technique described above needs to perform discrimination by a plurality of discriminators corresponding to different hidden areas from one another with respect to one pattern. For this reason, a processing cost is high, and subjects cannot be detected more efficiently. Further, in the conventional technique described above, a case where occurrence probability of the occlusions is varied depending on locations of the subjects is not considered.